What I mean by that is, does it continuously reduce driller creation each cycle? So that it goes from 6 drillers, then 5 drillers, then 4, 3, 2, 1?

I'm just a bit confused by the wording of his description.

It doesn't keep going down. All your factories produce 5 drillers instead of 6 (unless you have a foreman or something, then it's just one less of whatever you're supposed to get).